The present invention relates to an electronic control apparatus for internal combustion engines, and more particularly to an electronic ignition control apparatus of the type including a calculation circuit to calculate an optimum spark advance angle of the engine in dependence upon changes of the operating condition of the engine.
To adapt a conventional electronic ignition control apparatus of this kind to an internal combustion engine, it is required that the ignition control apparatus is specifically arranged in a complicated construction in accordance with such control specifications for the engine as the number of cylinders, the timing and extent for starting calculation of the engine speed, the timing for starting calculation of the ignition timing, and the like. This means that the ignition control apparatus is designed in a different construction on a basis of a different control specification for the respective engines. This results in high production cost of the control apparatus and late supply to demand of the control apparatus.